1. Field of the Invention
The present invention relates to electronic communication of messages, and more particularly, to security of these messages.
2. Description of Related Art
Systems for creating random number have been used in the past in different areas. One such use is for a random number generator for games simulating random chance.
Another use is for protecting the content of transmitted messages from interception by other parties which are not intended to receive the messages. Although an algorithm used to encode a message can be widely known, a secret keying variable should provide sufficient protection such that unwanted access can be prevented or made sufficiently difficult to guess to generally deter timely access.
Security algorithms typically turn a message to be sent, known as "plain text" into an encoded form known as "cipher text". The method is "reversible" so that the cipher text can be returned to plain text by an intended receiver.
Complex schemes of encoding tend to be very difficult for an non-intended receiver to guess the key and decode the message. However, these complex schemes may require much processing time during the encoding stage, when the message is being processed before it is transmitted, and during the decoding stage, when the encrypted message is received and converted back into its original form. The encoding and decoding stages are referred to as the "traffic" stages, whereas, the preparation of elements used in encoding or decoding are referred to as the "setup" stage.
Since it is desirable to send the message shortly after it is created and to be able to read the message shortly after it is received, it is desirable to have a scheme which requires little processing during the traffic phases. It is also desirable to have a scheme which is difficult to decode without the key.
Another use of a pseudorandom sequence is for "code spreading" in which a message to be sent is merged with a "spreading code" which is a pseudorandom sequence of a much faster rate to produce a signal with considerably larger bandwidth. This large bandwidth signal is transmitted on the same frequencies as other signals and separated out by an intended decoder. This is referred to as code division multiple access (CDMA).
Therefore there is a need for a system to quickly and easily provide a pseudorandom bit sequence which may be for a variety of purposes.